Expandable implant and implant system

ABSTRACT

An embodiment of the invention includes an expandable implant to endovascularly embolize an anatomical void or malformation, such as an aneurysm. An embodiment is comprised of a chain or linked sequence of expandable polymer foam elements. Another embodiment includes an elongated length of expandable polymer foam coupled to a backbone. Another embodiment includes a system for endovascular delivery of an expandable implant (e.g., shape memory polymer) to embolize an aneurysm. The system may include a microcatheter, a lumen-reducing collar coupled to the distal tip of the microcatheter, a flexible pushing element detachably coupled to an expandable implant, and a flexible tubular sheath inside of which the compressed implant and pushing element are pre-loaded. Other embodiments are described herein.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation of U.S. patent application Ser. No.15/984,003, filed May 18, 2018, which is a continuation of U.S. patentapplication Ser. No. 13/325,906, filed Dec. 14, 2011, now U.S. Pat. No.10,010,327, issued Jul. 3, 2018, which claims priority to both U.S.Provisional Patent Application No. 61/423,920, filed Dec. 16, 2010 andentitled “Apparatus for Endovascular Delivery of an Expandable AneurysmImplant”, and U.S. Provisional Patent Application No. 61/423,926 filedDec. 16, 2010 and entitled “Expandable Aneurysm Implant”. The content ofeach of the above applications is hereby incorporated by reference.

STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSOREDRESEARCH AND DEVELOPMENT

The United States Government has rights in this invention pursuant toContract No. DE-AC52-07NA27344 between the United States Department ofEnergy and Lawrence Livermore National Security, LLC for the operationof Lawrence Livermore National Laboratory.

FIELD

Various embodiments of the invention concern the treatment of anatomicalmalformations. Some embodiments concern delivery systems for implants.Some embodiments concern expandable embolic agents. Some embodimentsconcern endovascular embolization of aneurysms using an expandableembolic agent.

BACKGROUND

Cerebral aneurysms may develop when a weakened area of a blood vessel(e.g., a blood vessel in or around the brain) bulges outward. If nottreated, aneurysms can rupture resulting in hemorrhagic stroke, a majorcause of mortality and long-term disability. Taking cerebral aneurysmsfor example, there are several modalities used to treat cerebralaneurysms including: (1) traditional surgical clipping, and (2)endovascular embolization. Surgical clipping is a traumatic procedurethat involves craniotomy, retraction of the brain to expose theaneurysm, and placement of a metal clip across the aneurysm neck.Endovascular embolization is a minimally invasive technique in whichembolic agents are delivered into the aneurysm via a catheter, underfluoroscopic (x-ray) guidance, to occlude the aneurysm and promotehealing.

Regarding endovascular embolization, the Gugliemi Detachable Coil (GDC)allows a surgeon to deploy a helical platinum coil into the aneurysm.Once in proper position, the coil is detached from the deliveryapparatus and released into the aneurysm. Multiple coils may be requiredto effectively fill the aneurysm and induce clotting and eventualsealing of the aneurysm from the parent vessel. Such coils are subjectto problematic issues with recanalization and related insufficienthealing.

Though not as prevalent as embolic coils, liquid embolic agents thatsolidify inside the aneurysm are also available for clinical use in rarecases. However, such agents can be difficult to precisely administer atspecific sites.

BRIEF DESCRIPTION OF THE DRAWINGS

Features and advantages of embodiments of the present invention willbecome apparent from the appended claims, the following detaileddescription of one or more example embodiments, and the correspondingfigures, in which:

FIGS. 1A-F include an embodiment for embolization of an aneurysm with anexpandable apparatus delivered endovascularly.

FIGS. 2A, 2B, 2C-1, 2C-2 , D-F include embodiments of shape memorypolymer (SMP) elements, backbones, and monolithic SMPs covering longportions of backbones.

FIGS. 3A-D include embodiments in compressed pre-delivery stage anduncompressed, expanded post-delivery stage.

FIGS. 4A-B include an embodiment with spacers located between expandableelements.

FIG. 5 includes a heated carrier embodiment.

FIG. 6 includes an embodiment with a fiber optic light diffuser deliverymechanism.

FIG. 7 includes an embodiment with a fiber optic light diffuser deliverymechanism.

FIGS. 8A-B include a flexible embodiment of a monolithic SMP device.

FIGS. 9A-B include a flexible embodiment of a SMP device.

FIGS. 10A-B include a flexible embodiment of a tapered monolithic SMPdevice.

FIG. 11 includes a process for embolization of an aneurysm in anembodiment.

FIGS. 12A-B include an embodiment comprising a microcatheter, collar,and sheath.

FIGS. 13A-C include stages of delivery for embolization of an aneurysmin an embodiment.

FIGS. 14A-B include various embodiments for a sheath.

FIGS. 15A-B include an embodiment having a stop collar.

FIGS. 16A-I include an embodiment for a method of repositioning amisplaced embolization system.

FIG. 17 includes an embodiment with a sheath including apertures.

DETAILED DESCRIPTION

In the following description, numerous specific details are set forthbut embodiments of the invention may be practiced without these specificdetails. Well-known circuits, structures and techniques have not beenshown in detail to avoid obscuring an understanding of this description.“An embodiment”, “various embodiments” and the like indicateembodiment(s) so described may include particular features, structures,or characteristics, but not every embodiment necessarily includes theparticular features, structures, or characteristics. Some embodimentsmay have some, all, or none of the features described for otherembodiments. “First”, “second”, “third” and the like describe a commonobject and indicate different instances of like objects are beingreferred to. Such adjectives do not imply objects so described must bein a given sequence, either temporally, spatially, in ranking, or in anyother manner. “Connected” may indicate elements are in direct physicalor electrical contact with each other and “coupled” may indicateelements co-operate or interact with each other, but they may or may notbe in direct physical or electrical contact. Also, while similar or samenumbers may be used to designate same or similar parts in differentfigures, doing so does not mean all figures including similar or samenumbers constitute a single or same embodiment.

An embodiment of the invention includes an expandable implant toendovascularly embolize (fill) an anatomical void or malformation, suchas an aneurysm. An embodiment is comprised of a chain or linked sequenceof expandable polymer foam elements. Another embodiment includes anelongated length of expandable polymer foam coupled to a backbone.

The expandable polymer foam may comprise a shape memory polymer (SMP)foam in some embodiments. SMP foam is capable of being compressed andretaining its stable compressed shape (i.e., “secondary” state orconfiguration). The expandable foam element(s) may be compressedradially and/or extended/stretched axially for endovascular deliverythrough a microcatheter. The SMP may subsequently return to its stablepredetermined primary expanded form (i.e., “primary” state orconfiguration) when activated. Activation may include exposing the SMPto an appropriate stimulus (e.g., heat, electricity, light,electromagnetic energy, and the like). This transformation ability maybe based, at least in part, on the polymer morphology of the SMP. In anembodiment, the morphology comprises a shape-fixing matrix phase(amorphous or semi-crystalline polymer) and a shape-memorizing dispersedphase (physical or chemical crosslinks). The primary shape may beprogrammed into the material during the SMPs original melt processing orcuring process. The temporary secondary shape may be obtained bydeforming the SMP while heating the SMP above the characteristic thermaltransition temperature (Tt) and then cooling the SMP to fix the shape.In an embodiment, Tt may be the glass transition temperature (Tg) ormelting temperature (Tm) depending on the polymer system. The expandedSMP foam may serve as a localized scaffold for blood clot formation,which fosters the healing process of an aneurysm.

FIG. 1 includes an embodiment of the invention for embolization of ananeurysm with an expandable apparatus delivered endovascularly. In FIG.1(a) guide wire 110 is advanced into aneurysm 105. In FIG. 1(b)microcatheter 115 is advanced along guide wire 110 into aneurysm 105. InFIG. 1(c) guide wire is withdrawn and no longer showing, leavingcatheter 115 located in or near aneurysm 105. In FIG. 1(d) theexpandable implant, comprising backbone 120 and SMP elements 125, 126,127, is delivered from catheter 115 into aneurysm 105. FIG. 1(e) showsadditional length of backbone 120 and additional SMP elements deployedwithin aneurysm 105. In FIG. 1(f) backbone 120 is detached from guidewire 111. After FIG. 1(f) catheter 115 and guide wire 111 are withdrawnfrom the patient.

As used herein, “guide wire” is a general term that connotes a wire orrod used to guide itself or other items through vasculature. Guide wire111 may be thought of as a pusher rod that couples to backbone 120 toguide the backbone and SMP elements through catheter 115 and intoaneurysm 105.

FIG. 2 includes various embodiments including single and multiple SMPsystems. FIG. 2(a) includes an expandable aneurysm implant includingmultiple linked expandable elements (e.g., SMP foam). Expandable foamelements 201, 202, 203 (shown in expanded form) are spaced along asingle carrier element 205 (e.g., a backbone) extending axially throughall the expandable foam elements. FIG. 2(b) links SMP elements 210, 211,212 (shown in expanded form) together via linking elements 215, 216. Nosingle backbone extends through all the elements of FIG. 2(b).

FIG. 2(c)(i) shows how chain-like structure 220 maintains flexibilitydespite having elements 225, 226, 227 in compressed form. Compressedelements 225, 226, 227 are stiff and may present problems whennavigating the twists and turns of patient vasculature (e.g., smallcranial vasculature). However, spaces 228, 229 and the like allow system220 to bend and adapt to the twists and turns of patient vasculature,despite the stiffness of the compressed SMP foam. FIG. 2(c)(ii) showselements 225, 226, 227 in expanded form with the backbone and theelements in their primary states and deployed in a patient. The backbonemay include, for example, a shape memory alloy (e.g., Nitinol) that hasprimary and secondary states.

FIGS. 2(d) and 2(e) show backbones 230, 231 that are just two of themany configurations backbones may take in their relaxed primary states.Backbones 230, 231 may couple to numerous shorter elements (e.g., FIG.2(c)) or one or more longer elements (e.g., FIG. 2(f)). For example,FIG. 2(f) shows backbone 240 coupling to elongated, monolithic element245 (e.g., greater than 5 cm in length). Depending on stiffness ofbackbone 240 and element 245, system 246 may still maintain therequisite level of stiffness that facilitates advancing element 245through a deployment catheter while being flexible enough to navigatethe twists and turns of small vasculature.

FIG. 3 includes various embodiments in compressed pre-delivery stage anduncompressed, expanded post-delivery stage. FIG. 3(a) shows expandablefoam elements 310, 311, 312 coupled to backbone 306 and compressedradially (i.e., secondary state) for endovascular delivery throughmicrocatheter 305. FIG. 3(b) shows elements 310, 311 deployed fromcatheter 305 and expanded back to their primary state. FIG. 3(c) shows aseries of linked elements expanded within an aneurysm. FIG. 3(d) showsan embodiment where both single monolithic SMP 321 and backbone 320 areboth expanded into their respective primary states after being deliveredinto an aneurysm.

FIG. 4 includes an embodiment with spacers located between expandableelements. In FIG. 4(a) expandable foam elements 401, 402, 403 (shown inexpanded form) are coupled to carrier element 410 (e.g., backbone) andseparated from one another by wire coil spacers 421, 422. Wire coilspacers 421, 422 may be monolithic with carrier element 410 (e.g., wirecoiled spacers 421, 422 and carrier element 410 may be formed of asingle wire or rod that is straight at some sections and coiled atothers). In other embodiments, wire coil spacers 421, 422 may be looselyand non-fixedly coupled to carrier element 410. In other embodiments,wire coil spacers 421, 422 may be fixedly coupled (e.g., welded) tocarrier element 410. FIG. 4(b) shows the system of FIG. 4(a) includedwithin catheter 430 with expandable foam elements 401, 402, 403 shown incompressed secondary form. Spacers 421, 422 are coaxial with carrierelement 410. As seen in FIG. 4(b) the outer diameter of spacers 421, 422is equal to the compressed outer diameter of expandable foam elements401, 402, 403. Use of such spacers may facilitate pushing the SMP chainthrough a catheter. In other words, without the spacers there may bebunching between the SMP elements, which could frustrate advancement ofthe elements through the patient's vasculature.

FIG. 5 includes a heated carrier embodiment 500. Resistively heatedcarrier element 503 includes inner wire 505 and outer wire coil 504coupled together at distal end 506 to complete an electronic circuit.Expandable foam elements 501, 502 are shown in expanded form. In thisembodiment, a pushing element (not shown) containing two conductorscouples an external power supply to carrier 503. Current may flow fromthe power supply to carrier 503 to cause resistive heating of elements501, 502 to thereby transform elements 501, 502 from their secondarystates to their primary states.

FIG. 6 includes an embodiment 600 with a fiber optic light diffuser.Carrier element 603 includes inner flexible fiber optic light diffuser605 and outer wire coil 604. The fiber optic light diffuser 605 iscoupled to an external light source, such as a laser (not shown). Laserenergy is absorbed by outer wire coil 604, resulting in the heating ofcoil 604, causing expandable foam elements 601, 602 to expand to theirprimary states.

FIG. 7 includes an embodiment 700 with a flexible fiber optic lightdiffuser. The carrier element includes flexible fiber optic lightdiffuser 705. The fiber optic diffuser 705 is coupled to an externallight source, such as a laser (not shown). Laser energy is absorbed byexpandable foam elements 701, 702, resulting in heating of the foamscausing the expandable foam elements to expand to their primary states.

FIG. 8 includes a flexible embodiment for a foam configuration. In FIGS.8(a) and 8(b), system 800 includes backbone 810, which is coupled toguide wire (e.g., pusher wire) 805. Backbone 810 includes primary andsecondary states. For example, backbone may be formed from nickeltitanium (e.g., Nitinol). FIG. 8(a) shows backbone 810 in its secondarystate and FIG. 8(b) shows backbone 810 in its primary state. MonolithicSMP 811 (formed of a single piece of foam) covers a majority (>50%) ofbackbone 810. SMP 811 includes primary and secondary states, first andsecond portions 802, 803, and a first joint 822 located between thefirst and second portions.

In a first configuration as shown in FIG. 8(a), backbone 810 is coupledto pusher wire 805. SMP 811 and backbone 810 are both in theirrespective secondary states. In this configuration, system 800 isconfigured to be advanced through vasculature. For example, first andsecond portions 802, 803 are generally collinear with one another aswell as with portions 801, 804. Joints 821, 822, 823 are generallyclosed. However, joints 821, 822, 823 allow for flexibility as system800 navigates through curves in the vasculature.

In a second configuration as shown in FIG. 8(b), backbone 810 isdecoupled from the pusher wire (not shown), and monolithic SMP 811 andbackbone 810 are both in their respective primary states and configuredto both be included in an aneurysm. (Only a portion of the SMP is shown,and a longer version may look more like FIG. 2(f).) For example, SMP 811is expanded to fill, partially or fully, a void such as an aneurysm.Backbone 810 may transform from its secondary state (primarily straightor uncoiled) to its secondary state (coiled into a helix or coil such asshown in FIGS. 2 (d), (e), and (f). As seen in FIG. 8(b), first andsecond portions 802, 803 are non-collinear with one another based onfirst portion 802 pivoting about first joint 822 relative to secondportion 803. Also, portion 804 is pivoted about joint 823 and portion801 is pivoted about joint 821.

Joints 821, 822, 823 may include slits, which is broadly used herein toinclude, for example, an aperture, cut, slice, compression, notch,cleft, breach, cleavage, fissure, and/or split. As seen in FIG. 8(a),slit 822 includes a long axis 825 that is generally perpendicular to along axis of backbone 810 (which runs the length of backbone 810). Also,slit 822 extends less than 360 degrees about backbone 810. In FIG. 8(a)slit 822 extends approximately 320 degrees about the backbone but otherembodiments may extend, for example, 50, 100, 150, 200, 250, 300 degreesand the like. In an embodiment, slits may extend a full 360 degreesabout backbone 810 but not extend from the exterior surface of SMP 811all the way to backbone 810, thereby keeping 811 monolithic withportions 801, 802, 803, 804 not completely severed from one another.

As shown in FIG. 8(a), slit 821 is included in a superior exteriorsurface of SMP 811 and slit 822 is distal to slit 821 and included in aninferior exterior surface of SMP 811 but not the superior exteriorsurface of the monolithic SMP. Thus, the slits are staggered to allowfor flexibility while maintaining SMP 811 as monolithic (consideringslits 821, 822, 823 do not completely sever portions 801, 802, 803, 804from one another).

In an embodiment, SMP 811 is greater than 5 cm in length and is the onlySMP coupled to backbone 810. In other embodiments the only SMP coupledto the backbone may be longer or shorter and include lengths of, forexample, 3, 4, 6, 7, 8, 9 cm and the like.

Further, in an embodiment the SMP in the secondary state has a modulusthat is greater than the SMP's modulus in the primary state. Forexample, the SMP is stiffer when being pushed through a catheter andinto the body, but softer and more compliant when deployed in ananeurysm and pushed up against delicate aneurysm walls.

In FIG. 8(a) in their secondary states all of portions 801, 802, 803,and 804 are flush against one another. This may facilitate smoothlyadvancing SMP 811 within a catheter as there are no edges exposed tocatch on various obstacles that may be encountered during deployment. Asshown in FIG. 8(a) portion 801 includes a distal face (i.e., distal faceformed by slit 821) that is complimentary to and flush against theproximal face of portion 802 (i.e., proximal face formed by slit 821).

However, in FIG. 8(b) the portions are not all completely flush againstone another due to pivoting (e.g., slit 821 is opened partially). Thismay expose extra surface area (e.g., inside surfaces of slit 821) toblood flow to facilitate clotting and aneurysm healing.

In one embodiment, SMP 811 fixedly adheres to backbone 810 when both arein their primary states and implanted in a patient. For example, anadhesive may couple SMP 811 to backbone 810 (possibly applied in a thinlayer over backbone 810). Such adhesives include, for example, epoxy,urethane, acrylate, methacrylate, urethane acrylate, and the like.Options include adhesives that function either through mechanicaladhesion and/or chemical adhesion (e.g., covalent, ionic, polar, orVander Waals coupling forces). For example, a urethane adhesive may beuseful due to its ability to chemically bond to both SMP 811 andbackbone 810 (which includes a metal surface in some embodiments). Inanother embodiment, the adhesive could be SMP 811 itself so SMP fixedlyadheres directly to backbone 810. For example, a urethane SMP may adheredirectly to backbone 810 without need for an adhesive layer coupling SMP811 to backbone 810. In other words the urethane of a urethane SMP mayprovide for coupling to the backbone without an additional adhesivelayer because the “wet” urethane functions as an adhesive. In anotherembodiment, SMP 811 includes a thermoplastic SMP adhesive obtained byheating backbone 811 to the melting point of SMP 811 such that SMP 811wets backbone 810 and develops a direct bond between SMP 811 andbackbone 810. In an embodiment, adhering a cured polymer foam (e.g., theSMP to be used to embolize the aneurysm) to a backbone may be done witha liquid thermoset SMP. The thermoset may be of the same type of foam asthe embolizing foam. Thus, a first layer of SMP adheres to the backboneand then another layer of SMP adheres to the first SMP. The first layer(the thermoset) could be slightly different (e.g., a different Tg) fromthe second layer SMP and could have additives that benefit theapplication (e.g., radio opaque particles like tungsten).

In another embodiment, backbone 810 may be sufficiently bonded or fixedto SMP 811 through mechanical friction. The basis for the friction forceis the friction between SMP 811 and backbone material 810 and the normalstress applied by previously stretched material (such as a axiallystretched SMP in its secondary state). Above SMP embodiments thatfixedly adhere directly to backbone 810 (when both are in their primarystates when implanted in a patient) contrast with, for example,hydrogels that are not adhesive (especially not when “wet” as is thecase when implanted in a patient).

FIGS. 10 (a) and (b) include embodiments similar to FIG. 8 in that SMP850, located on backbone 851 which is coupled to pusher elements 864, ismonolithic and comprised of portions 861, 862, 863; none of which arecompletely severed from one another. Joints 852, 853 allow portions 861,862, 863 to pivot with regard to one another. Pivoting may befacilitated considering portion 862 includes a face that tapers from arelatively thinner proximal portion 854 to a relatively thicker distalportion 855. The tapering may facilitate the ability to retract foam 850back into a catheter if, for example, SMP 850 is properly placed in ananeurysm but then becomes improperly placed outside the aneurysm. If SMP850 has already begun to expand the tapered portions facilitateretracting the SMP back into the catheter.

FIG. 11 includes process 1100 in an embodiment of the invention. Block1105 provides a system comprising a backbone (the backbone being coupledto a pusher wire and including primary and secondary states) and acatheter. A SMP, which covers a majority of the backbone, may bedeployed within the catheter. The SMP may be a monolithic SMP including:(a) primary and secondary states, (b) first and second portions, and (c)a first joint located between the first and second portions.

Block 1110 includes advancing the system through a patient'svasculature, using a pusher wire that is coupled to the backbone. Forexample, the catheter may be placed in the aneurysm and then thebackbone/SMP are advanced through the catheter. While doing so, themonolithic SMP and the backbone are both in their respective secondarystates, and the first and second portions are generally collinear withone another.

Block 1115 includes deploying the first joint from the catheter and intothe patient. Block 1120 includes withdrawing the deployed first jointfrom the patient and back into the catheter. Block 1120 may be necessaryif the SMP becomes misplaced. Various configurations, such as theconfiguration of FIGS. 8, 9, 10 , may facilitate the ability to withdrawthe jointed sections back into the catheter.

Block 1125 includes locating the monolithic SMP and the backbone, bothin their respective primary states, in an aneurysm, the first and secondportions being non-collinear with one another based on the first portionpivoting about the joint relative to the second portion.

FIGS. 9A-B include an embodiment having a flexible SMP 836.Specifically, backbone 834 includes primary and secondary states. SMPportions 831, 832 collectively cover a majority of the backbone thatcouples to pusher element 835. Portions 831, 832 each include primaryand secondary states. Joint 833 is located between portions 831, 832. Ina first configuration (FIG. 9(a)) portions 831, 832 and backbone 834 areall in their respective secondary states and configured to be advancedthrough vasculature. In a second configuration (FIG. 9(b)) portions 831,832 and backbone 834 are all in their respective primary states andconfigured to all be included in an aneurysm. In the secondconfiguration portion 831 pivots about joint 833, with respect toportion 832, when portions 831, 832 and backbone 834 are all in theirrespective primary states. At least part of portion 831 is flush againstat least part of portion 832 when in the first configuration. In FIG.9(a) portions 831, 832 are completely flush against each other. Thisportion 831 face being flush to a portion 832 face may facilitatedeployment of the SMP portions through a catheter or sheath. This mayalso facilitate withdrawal of the SMP portion 831, 832 back into thecatheter or sheath if the portions are misplaced (e.g., in a parentartery).

FIG. 9(a) only shows two portions but certainly more portions and morejoints may be included. In an embodiment, portions 831 and 832 arecompletely severed from one another. However, in another embodimentportions 831, 832 are not completely severed from one another andinstead are part of a single monolithic SMP. Such an embodiment mayinclude a deep cut to form joint 833. The cut may be deep but notsurround backbone 834 by 360 degrees and/or may not extend all the wayto backbone 834. Either or both of portions 831, 832 may be fixedlycoupled to backbone 834. However, one or both of portions 831, 832 maybe non-fixedly coupled (e.g., slidably coupled) to backbone 834.

An embodiment includes a system comprising a backbone including primaryand secondary states; and a monolithic SMP covering a majority of thebackbone. The SMP includes first and second portions. The SMP pivots thefirst portion about the second portion when the monolithic SMP and thebackbone are both in their respective primary states and also when themonolithic SMP and the backbone are both in their respective secondarystates. Thus, in one embodiment the backbone and SMP may include astiffness configured to allow flexibility and pivoting when traversingthe patient's vasculature. However, the stiffness may still be such thatwhen the backbone and SMP are in their primary states (e.g., whendeployed into an aneurysm and expanded) the portions of the SMP maypivot about one another as the backbone takes its shape (e.g., helicalshape) and/or the elements expand. In such a situation the SMP may notnecessarily include joints such as those found in FIGS. 8, 9, and 10 .Instead, the SMP may, for example, be in the shape of a simple solidcylinder that runs along a majority of the backbone. The backbone may becentered within the cylinder. FIG. 2(f) includes an example of ajointless SMP that covers a majority (>50%) of a backbone.

The SMP foam elements described herein may be cylindrical, ellipsoidal,spherical, diamond or other shape in their expanded form. The expandablefoam elements may be identical or may have different shapes, sizes,and/or spacing within a single device. For example, different portionsof a single SMP may have different shapes (such as portions 861 and 862of FIG. 10(a)). This also applies to devices with several differentfoams in a single device (e.g., FIG. 2(a)).

As shown above, a device may contain any number of foam elements (FIG. 2(c)), including a single foam element along the entire length (or amajority of the length) of the carrier element (FIG. 2(f)). The shape ofthe single foam element may be patterned to retain flexibility in thecompressed state while permitting retraction back into the microcatheterafter expansion. This patterning may include the use of joints asdescribed in regards to FIGS. 8-10 . Another example of patterning is toinclude alternating diamonds of foam. In a given length of the SMP theremay be two diamonds on opposite sides. The adjoining sections, bothproximal and distal (to non-terminal segments) have two diamonds rotatedby 90 degrees with the axial points of the diamonds overlapping. Asimilar pattern may be applied in the case of multiple foam elements.

Some embodiments may avoid or limit axially abrupt changes indiameter/materials along the length of the device that could catch onthe edge of the microcatheter during retraction (e.g., FIG. 10 ).

In one embodiment, the expandable foam elements are spaced along asingle carrier element extending axially through all the expandable foamelements. The carrier element may be comprised of a wire filament (e.g.Nitinol), a GDC-like wound wire coil, or a combination of both.Alternatively, the carrier element may be a polymer strand, andspecifically may be a SMP. The carrier element may assume a straightenedform during endovascular delivery through a microcatheter. The carrierelement may assume a helical or other complex 3D shape when deliveredout of the microcatheter and into the aneurysm. The expandable foamelements may be bonded to the carrier element to maintain their spacing.The spaces between expandable foam elements may be occupied bycylindrical flexible spacer elements having the same outer diameter asthe foam elements in their compressed form. The flexible spacer elementsmay be wire coils (see above), SMP foam, or other flexible material. Inanother embodiment, the carrier element may consist of alternatingstraight and coiled sections with the expandable foam elements placedover the straight sections and the coiled sections serving as spacers(See FIG. 4 ).

The expanded foam in various embodiments acts a scaffold for clotformation within the open celled SMP structure. The scaffold nature ofthe foam may work with the body's healing response to initially clot,endothelialize the neck of the aneurysm, and, finally, remodel the clotwith extra cellular matrix (including collagen). Throughout this healingprocess, the SMP scaffold stabilizes the treated aneurysm and permitsthe natural healing process to occur. In contrast, metallic coilsprovide minimal support to the large volume of clot that surrounds them(clots typically make up 60-90% of the total aneurysm volume), andhydrogels block out clotting and normal healing with their small porestructure. The scaffold nature of the foams is beneficial in healing ofaneurysms.

The SMP foam may expand spontaneously upon delivery into the aneurysm(e.g. Tg≤body temperature) or may require an external energy source toachieve expansion (e.g., laser heating, resistive heating, heated fluidflush, inductive heating, and the like). If an external energy source isused, the device may be retracted back into the microcatheter ifnecessary prior to expansion. In one embodiment, the carrier elementserves as a resistive heater by passing a current through the carrierelement (See FIG. 5 ).

In an embodiment, all or part of the carrier element is comprised ofmagnetic material and is heated inductively by an external magneticfield. In an embodiment, the expandable foam elements are doped withmagnetic particles and heated inductively by an external magnetic field.In an embodiment, a flexible fiber optic light diffuser is positionedinside the carrier element (e.g., FIGS. 6, 7 ); the carrier elementabsorbs the laser light and is heated, which in turn heats theexpandable foam elements. In an embodiment, the expandable foam elementsare doped with laser absorbing dye or particles and a flexible fiberoptic light diffuser serves as the carrier element (FIGS. 6, 7 ); thedoped expandable foam elements absorb laser light and are heated.

In the case of a heated carrier element comprised of a polymer strand,the polymer strand may be doped with conductive particles (e.g. carbon,metallic, etc.) distributed to form a current path for resistive heatingof the polymer strand. Alternatively, the polymer strand may be dopedwith magnetic particles for inductive heating or laser absorbingdye/particles for laser heating.

A degradable membrane may be used to encapsulate/restrain the compressedfoam elements during endovascular delivery, facilitating transportthrough the microcatheter and retraction back into the microcatheter ifplacement in the aneurysm is not satisfactory. The membrane may becomprised of a water or blood soluble/degradable polymer, thermallydegradable polymer, or otherwise degradable material. Thermaldegradation may be accomplished spontaneously at body temperature or athigher temperature by a heated fluid flush or other heating mechanism(e.g., laser heating, resistive heating, electromagnetic heating, orinductive heating). The membrane may be applied over the compressedexpandable foam elements by dip-coating or other suitable means, or themembrane may be a tubular form in which the compressed device can beinserted. Bioactive (e.g. clotting) agents may be incorporated into anypart of a device, including the expandable foam elements, the carrierelement or linking elements, or the degradable restraining membrane, toenhance the healing response.

Above much discussion has been made regarding various malformationfilling devices (e.g., SMP foam) that are implanted in a patient.Discussion now turns towards devices and systems for implantingmalformation filling devices (e.g., SMP devices).

An embodiment provides a system for endovascular delivery of anexpandable implant to embolize an aneurysm. FIG. 12 includes anembodiment comprising microcatheter 1220, lumen-reducing collar 1225coupled to the distal tip of microcatheter 1220, flexible pushingelement 1205 detachably coupled to an expandable implant (e.g., SMPfoam), and flexible tubular sheath 1215 inside of which the compressedimplant and pushing element are pre-loaded.

By preloading the SMP implant within the sheath, the sheath can moreeasily slide within the microcatheter (along with the SMP inside thesheath) than would be the case if the SMP foam were to be forced toslide along the inside of the microcatheter (i.e., with no sheath bufferbetween the foam and the stationary microcatheter that has already beenlocated in the aneurysm before the implant is introduced into thepatient). Sliding the SMP foam along the inside of the catheter may bedifficult considering the friction between the microcatheter and the SMPfoam. Thus, the flexible tubular sheath facilitates transport of thecompressed expandable implant through the microcatheter. In oneembodiment, by advancing the flexible tubular sheath out of themicrocatheter with the expandable implant still inside the sheath, theflexible tubular sheath provides the ability to assess the stability ofthe microcatheter position prior to deployment of the expandableimplant, which potentially may not be retracted once deployed. If themicrocatheter moves out of proper position while the flexible tubularsheath (with the compressed expandable implant still inside) is advancedbeyond the distal tip of the microcatheter, the sheath can be retractedto allow re-positioning of the microcatheter. Also, the flexible tubularsheath may be used to restrain the compressed expandable implant. Inconventional systems the compressed implant is restrained solely by themicrocatheter itself.

Using standard fluoroscopic interventional techniques, the distal tip ofthe microcatheter is positioned in the neck of the aneurysm. Theflexible tubular sheath 1215 (containing the flexible pushing element1205 and an expandable implant) is passed through the microcatheteruntil it is stopped by lumen-reducing collar 1225. Flexible pushingelement 1205 is then advanced distally until the expandable implantemerges from flexible tubular sheath 1215 and is delivered into theaneurysm. Finally, the expandable implant is detached from flexiblepushing element 1205 using suitable means (electrical, mechanical,optical, and the like) coupled to the system.

FIG. 13 includes stages of delivery for one embodiment of the invention.FIG. 13(a) includes pushing element 1305 pushing implant 1306 along with(i.e., simultaneously) sheath 1315, all within microcatheter 1320.Expandable implant 1306 is contained inside flexible tubular sheath1315. FIG. 13(b) shows collar 1325 blocking sheath 1315 while implant1306 continues to be pushed by pushing element 1305. Implant 1306 ispictured moving while sheath 1315 is stationary. In other words, pushingelement 1305 and flexible tubular sheath 1315 are advanced throughmicrocatheter 1320 until the sheath is stopped by lumen-reducing collar1325. The pushing element continues to advance causing the expandableimplant to emerge from the sheath and the microcatheter. FIG. 13(c)shows pushing element 1305 near the distal end of catheter 1320, withimplant 1306 deployed from catheter 1320 and decoupled from pusherelement 1305.

Returning to FIG. 12 , manual clamping fixture 1211 (e.g., O-ringcompression fitting) is included on the proximal end of microcatheter1220 to fix the position of inner flexible tubular sheath 1215. Secondmanual clamping fixture 1210 is incorporated on the proximal end offlexible tubular sheath 1215 to fix the position of inner pushingelement 1205. The clamping fixtures can be opened to allow movement ofthe inner components as necessary.

Thus, FIG. 12 provides an apparatus for endovascular delivery of anexpandable implant into an aneurysm. The lumen-reducing collar at thedistal tip of the microcatheter stops the flexible tubular sheath, inwhich the pushing element and expandable implant are pre-loaded, whileallowing the expandable implant to exit the microcatheter. The clampingfixture at the proximal end of the microcatheter may be used to fix theposition of the flexible tubular sheath. The clamping fixture at theproximal end of the flexible tubular sheath may be used to fix theposition of the pushing element.

In one embodiment one or more radiopaque markers (e.g., platinum bands)are incorporated into the distal portion of microcatheter 1220 tofacilitate navigation under fluoroscopy. Lumen-reducing collar 1225 mayserve as one of the markers. Pushing element 1205 may be entirelyradio-opaque to enable fluoroscopic visualization of its position.Flexible tubular sheath 1215 may not be 100% radio-opaque so it does notobscure the pushing element. The expandable foam element(s) themselvesmay be radio-opaque by incorporating radio-opaque elements (atomicallyor as particles) into a polymer used for the foam during the foamformulation process. The backbone and/or linking elements (see FIG.2(b)) may also be radio-opaque.

As indicated above and as indicated in FIG. 13 , a purpose of flexibletubular sheath 1315 is to allow pre-loading of compressed expandableimplant 1306 within sheath 1315. This removes the need to passcompressed expandable implant 1306 through the entire length ofmicrocatheter 1320 with no buffer between foam 1306 and catheter 1320.Because in one embodiment the compressed expandable implant 1306 ispre-loaded at the distal end of flexible tubular sheath 1315, itsdeployment into the aneurysm only requires pushing it (in relation tosheath 1315) a relatively short distance (e.g., length of the compressedexpandable implant).

Further regarding FIG. 13 , lumen-reducing collar 1325 may serve toprevent (1) flexible tubular sheath 1315 from exiting microcatheter1320, and (2) axial stretching of flexible tubular sheath 1315 aspushing element 1305 is advanced to deliver expandable implant 1306.

FIG. 14 includes various embodiments for a sheath in an embodiment ofthe invention. Flexible tubular sheath 1415 may include metal round wirecoil 1416, metal ribbon (flat) wire coil 1417, and the like.

In an embodiment, a flexible tubular sheath may be comprised of multiplesections, each section decreasing in stiffness from proximal to distal.For example, a two-section sheath may be comprised of a proximal solidmetal tube and a distal metal ribbon wire coil. A thin polymer coatingmay be applied over the metal to inhibit axial (i.e., lengthwise)stretching of the coil. As another example, the sheath may include anintermediate portion centrally located between a proximal end portion ofthe sheath and the distal end portion of the sheath, and the distal endportion of the sheath may be more flexible than the intermediate portionof the sheath.

FIG. 15 includes an embodiment having a stop collar. In FIG. 15 (a) theflexible tubular sheath has been partially advanced. In FIG. 15 (b) theflexible tubular sheath has reached maximum advancement. The stop-collarmay mitigate the potential inability to recapture the expandable implantafter it has emerged from the flexible tubular sheath. A stop-collar ispositioned on the flexible tubular sheath such that the sheath mayadvance a fixed distance before or beyond the distal tip of themicrocatheter. For example, stop-collar 1525 is located on the outsideof the proximal end of flexible tubular sheath 1515 such that sheath1515 cannot advance beyond the distal tip of the microcatheter 1520 (seeFIG. 15(b)) due to cinching element 1511. If flexible tubular sheath1515 is constructed such that it is not susceptible/not highlysusceptible to axial stretching (e.g., polymer-coated metal wire coil),the need for lumen-reducing collar 1325 (as shown in FIG. 13 ) may bediminished. Similarly, a stop-collar may be located on pushing element1505 (to interface cinching element 1510) such that the detachment pointbetween pushing element 1505 and an expandable implant is near thedistal end of flexible tubular sheath 1515 after the expandable implantis delivered into the aneurysm lumen.

Thus, in one embodiment a stop-collar on a flexible tubular sheath maybe used instead of a lumen-reducing collar at the distal tip of themicrocatheter. The lumen-reducing collar, stop collar, or combinationsthereof may all prevent advancing the sheath from extending beyond(fully or partially) the distal tip of the microcatheter.

FIG. 16 includes an embodiment for repositioning a misplaced system. Asaddressed above in regards to FIG. 12 , the sheath allows forrepositioning a misplaced system. Along these lines, FIGS. 16(a)-(c)depict locating guide wire 1601 and then microcatheter 1620 within ananeurysm. Flexible tubular sheath 1615 and its contents (e.g.,expandable implant and detachably coupled flexible pushing element) areadvanced through microcatheter 1620. More specifically, in FIG. 16 (a)the guide wire is advanced into the aneurysm; in FIG. 16 (b) themicrocatheter is advanced along the guide wire into the aneurysm; and inFIG. 16 (c) the guide wire is withdrawn. In FIG. 16(d) microcatheter1620 moves out of the aneurysm neck during advancement of flexibletubular sheath 1615, and sheath 1615 is mistakenly advanced into theparent artery instead of the aneurysm lumen. For example, the flexibletubular sheath (containing the expandable implant) is passed through themicrocatheter and improperly advanced into the parent vessel instead ofthe aneurysm due to instability of the microcatheter.

To remedy the situation sheath 1615 and its contents are retracted backinto microcatheter 1620 and fully withdrawn from catheter 1620. Thenguide wire 1601 is re-inserted and repositioned in the aneurysm,followed by repositioning catheter 1620 along the guide wire in theaneurysm (FIGS. 16(e) and (f)). The guide wire is withdrawn and theflexible tubular sheath 1615 (containing the expandable implant) ispassed through the microcatheter and properly advanced into the aneurysm(FIG. 16(g)). In FIG. 16(h) one or more embolizing elements (e.g., SMPs)are deployed and the backbone/pusher rod coupling is severed in FIG. 16(i) (i.e., the expandable implant (e.g., backbone) is detached from thepushing element (e.g., pusher rod) and the remainder of the apparatus iswithdrawn).

Thus, if the microcatheter moves out of the aneurysm neck after theflexible tubular sheath has been advanced slightly into the aneurysmlumen, and the sheath is still inside the aneurysm lumen, themicrocatheter may be re-positioned in the aneurysm neck if necessary,using the protruding sheath as a guide wire. If the microcatheterposition is stable following slight advancement of the flexible tubularsheath into the aneurysm lumen, the flexible pushing element may then beadvanced distally until the expandable implant emerges from the flexibletubular sheath and is delivered into the aneurysm. The expandableimplant is then detached from the flexible pushing element. In theembodiment of FIG. 16 , the flexible tubular sheath is constructed suchthat it is not susceptible to axial stretching (e.g., polymer-coatedmetal wire coil).

FIG. 17 includes an embodiment with a sheath including apertures.Flexible tubular sheath 1715 may contain two or more axial slits (e.g.,1718, 1719) extending from the distal tip of the sheath to some pointmore proximal on the sheath. Slits 1718, 1719 allow sheath 1715 to havemembers 1716, 1717 that expand when advanced beyond the distal end ofthe microcatheter 1720. This expansion reduces the friction betweenexpandable implant 1706 and sheath 1715 as the implant is pushed out ofthe sheath. As another example, the sheath may include an opening, atthe distal tip of the sheath, through which the unexpanded implantdeploys. The sheath may also include one or more sidewall openings,coterminous with the opening at the distal tip of the sheath, formingone or more branches that expand after deployment from themicrocatheter. Including only a single sidewall opening may still allowsufficient expansion to accommodate retrieving the foam (expanded orunexpanded) back into the sheath. In an embodiment, the foam may then bewithdrawn back into the catheter.

In an embodiment the flexible tubular sheath may be comprised of adegradable material that is water and/or blood soluble, pH sensitive,and the like. The pushing element may comprise a detachment mechanism tosevere or cut the sheath after it is pushed into the aneurysm. Thesheath may then degrade within minutes allowing the expandable implantto fully deploy.

In one embodiment, an attachment element exists between the pushingelement and expandable implant. The attachment element can be used topull back, or retrieve, a partially delivered expandable implant. Theattachment element can be heated via applied energy (e.g., optical orelectric energy) to induce detachment of the expandable implant. Theapplied energy can also be used to expand the expandable implant priorto detachment at the discretion of the operator (e.g., in the case wherethe expandable implant requires external energy to induce expansion).

An embodiment of the attachment element includes a polymer section dopedwith conductive particles. The conductive particles can be selectivelyheated to heat the attachment element using, for example, electricalcurrent delivered via wires inside the pushing element. If onlydetachment of the expandable implant is desired, the doping particles(e.g., carbon and/or metallic particles) are distributed throughout theattachment element. If combined expansion and detachment of theexpandable implant is desired, the doping particles may be localized soas to make conductive paths between the wires in the pushing element andwires (and/or conductively doped polymer) in the expandable implant.

Again regarding FIG. 13 , one embodiment includes a system comprising anunexpanded implant having a maximum outer diameter (D1); a flexiblehollow sheath, including a maximum outer diameter (D3), with theunexpanded implant pre-loaded in a distal end portion of the sheath; aflexible hollow microcatheter including a body having a maximum innerdiameter (D4); and a collar, coupled to the microcatheter, having amaximum inner diameter (D2). The maximum inner diameter of themicrocatheter body (D4) is greater than the maximum outer diameter ofthe sheath (D3). The maximum outer diameter of the sheath (D3) isgreater than the maximum inner diameter of the collar (D2). The maximuminner diameter of the collar (D2) is greater than the maximum outerdiameter of the unexpanded implant (D1). Based at least in part on D1,D2, D3, D4, the sheath and pre-loaded unexpanded implant maysimultaneously advance within the microcatheter. Advancement of thesheath is eventually halted by the collar. Also, the unexpanded implantmay advance past the collar and the halted sheath and into a patient.

In an embodiment, the sheath may be stretchable along its long axis.However, the collar may block advancement of the sheath and lessen axialstretching of the sheath when deploying the unexpanded implant from thesheath.

In an embodiment, the sheath, when deployed from the microcatheter, (a)prevents the unexpanded implant from expanding, and (b) permits theunexpanded implant, located within the sheath, to be retracted back intothe microcatheter after having been deployed from the microcatheter.

In an embodiment, the maximum outer diameter of the sheath is locatedproximal to the distal end portion of the sheath. In such a case, distalportions of the sheath may be allowed past (or distal) the collar. Themore proximally located maximum diameter of the sheath may eventually bestopped by the collar, but not until after the distal portion of thesheath has extended past the collar and past the tip of themicrocatheter.

In an embodiment the microcatheter and the collar are monolithic withone another (e.g., formed from a single mold). Doing so may help ensurethe collar does not separate from the catheter when the implant (e.g.,foam) is pushed out from the catheter and into the patient. Also, thecollar may include a circular opening from which the unexpanded implantis deployed. However, other shapes are possible (e.g., ovular).

Also, in an embodiment the unexpanded implant is preloaded near thedistal end portion of the sheath before the sheath is deployed into themicrocatheter. This may shorten the distance that the implant may needto be pushed while the sheath is stationary. In other words, ifresistance based on the foam is high then deployment of the foam isfacilitated by shortening the distance the foam must travel (whilepushing against side walls of the sheath) while the sheath isstationary.

In an embodiment, the unexpanded implant comprises a SMP having a glasstransition temperature (Tg) less than 100 degrees Fahrenheit. Such anSMP may expand to its primary shape based on body temperature.

An embodiment includes a SMP that covers a majority of the backbone andis greater than 5 cm in length. However, other lengths including 3, 4,6, 7, 8, 9 cm and the like are included in other embodiments.

In an embodiment a retainer (that stops sheath advancement) may belocated proximal to the proximal tip of the microcatheter when theimplant advances past the distal tip of the halted sheath and into apatient. Such a retainer may be a collar located proximal to the distalend of a catheter. The retainer may be similar to collar 1325, clamps1210 and 1211, collar 1525, and the like.

An embodiment includes a sheath that (a) prevents the implant fromexpanding, and/or (b) permits the implant, while located within thesheath, to be retracted back into the catheter after having beendeployed from the catheter.

An embodiment includes a sheath that is configured so, when deployedfrom the catheter, the sheath permits the already expanded implant to beretracted back into the sheath, compressed within the sheath, and thenretracted back into the catheter.

Another embodiment includes a method comprising: providing an expandableimplant, a flexible hollow sheath, a flexible hollow catheter, and aretainer coupled to the catheter. A user may insert the catheter,sheath, and implant into a patient and then (a) simultaneously advancethe sheath and the implant within the catheter until the sheath ishalted by the retainer; and (b) advance the implant past the retainer,out from the sheath, and into the patient. In one embodiment, thesimultaneous advancement is fostered by the implant being loaded in thesheath before inserting the sheath into the patient.

An embodiment may allow (after advancing the implant into the patientand expanding the deployed implant) simultaneously retracting theexpanded implant and the sheath back into the catheter. The may befacilitated based on the modulus of the expanded implant (i.e., thestiffness of the expanded implant may be such that it can be withdrawninto the sheath and/or catheter). The method may further allowcompressing the expanded implant within the sheath based on retractingthe sheath back into the catheter.

In one embodiment, the microcatheter may include an inner diameter ofapproximately 0.483 mm and the SMP may include a volume expansion of80×. A 10 mm diameter aneurysm may require more than a single piece offoam. As described above, several embodiments including one or moreexpansion elements are disclosed. One such embodiment includes a SMPfoam formed over a wire backbone with a 3D form. Depending on the 3Dgeometry of the wire backbone, one SMP foam may adequately fill theaneurysm with a single deployment. However, in other embodiments one mayapply a “Russian doll” method that requires multiple (e.g., 2, 3, ormore) deployments using devices with successively smaller 3D geometries.In addition, in an embodiment one may initially deploy a standard 3D“framing” coil followed by any of the various embodiments describedherein. Also, any of the various embodiments described herein may serveas a framing structure followed by deployment of coils (e.g., GDCs).

One embodiment includes a SMP foam on a wire (e.g. Nitinol, platinum)backbone that is delivered into an anatomical void (e.g., aneurysm). Forexample, a polymer coated (to bond with foam) wire backbone (0.050 mmdiameter) with 3D primary form or state (e.g., about 10-20 cm long instraight form). The embodiment may include a SMP foam with 80× volumeexpansion (e.g., about 9× radial expansion with expanded diameter ofabout 4.5 mm); expansion at body temperature; cylindrical sections(e.g., each about 1 to 5 mm long) bonded to wire backbone. The sectionswould provide flexibility in collapsed form. There may be a compressedouter diameter of about 0.33 mm and an expanded diameter of about 2.9mm. Other embodiments include varying expansion capacities such as, forexample, 20×, 40×, 60× (expanded diameter of about 3.9 mm), 100× and thelike. Embodiments may include SMPs with varying Tg such as 37, 39, 41,43 degrees Celsius.

An embodiment may include a microcatheter with a self-centering distalstop. The catheter may have the following dimensions: 2.0F; 0.667 mmouter diameter; 0.483 mm inner diameter. A distal stop (e.g., collar ofFIG. 13 ) halts sheath advancement as foam is pushed out. The distaledge of the collar may be rounded to facilitate retraction of expandedfoam back into the sheath prior to detachment of the foam from thedeployment system.

An embodiment may include a sheath that confines compressed foam fortransport through a microcatheter. This sheath may include a flexibleround wire or ribbon (flattened wire) coil, Teflon tube, and the likehaving dimensions such as, for example, 0.433 mm outer diameter and0.333 mm inner diameter.

An embodiment may include a pusher to transport sheathed foam through amicrocatheter and push compressed foam out of the sheath. A flexibleguide wire (i.e., a pusher rod) may be used and may include a ≤0.333 mmdiameter (pushable through sheath) having a step transition (e.g.,collar or band of FIG. 13 ) to prevent over pushing. The pusher may alsoinclude a mechanism to temporarily anchor the sheath to the pusher untilthe sheath reaches the distal stop (e.g., grooves on the pusher toaccept rounded teeth on the proximal inner surface of the sheath). Thismay be used if the wire-foam is not attached to the pusher.

An embodiment may use a detachment mechanism (e.g., electrical) at thejunction between the pusher and the wire-foam.

An embodiment may use a guide wire that serves as a pusher. The guidewire may be similar to commonly used guide wires. However, in anotherembodiment one such guide wire may include a floppy distal end, whichonce removed, may serve as the pusher. The confining sheath may be sizedaccording to the pusher diameter. A detachment mechanism may not beincluded in all embodiments (i.e., the wire backbone may not be attachedto the pusher).

In an embodiment, the foam may be compressed around the wire backbonewithout being bonded to the backbone. As a result, the foam may not befixedly coupled to the backbone (e.g., the foam may be able to slidealong the backbone) or it may be fixedly coupled to the backbone (e.g.,the foam may be unable to slide along the backbone due to, for example,friction between the foam and backbone). In such scenarios the need tocoat the wire or synthesize the foam around the wire may be unnecessary.Multiple foam cylinders may be threaded by hand over the bare wire.

Embodiments are not limited to cerebral aneurysms or even aneurysms forthat matter. For example, embodiments may be used as implants to fillanatomic voids (e.g., foramen ovale and the like). Embodiments are notlimited to SMPs but may use other void filling systems such as otherexpandable embolizing systems.

While the present invention has been described with respect to a limitednumber of embodiments, those skilled in the art will appreciate numerousmodifications and variations therefrom. It is intended that the appendedclaims cover all such modifications and variations as fall within thetrue spirit and scope of this present invention.

What is claimed is:
 1. An implantable system to fill an anatomic void,the system comprising: a carrier element; and a shape memory polymerfoam covering a majority of the carrier element, the shape memorypolymer foam having primary and secondary shapes and including first andsecond shape memory polymer portions; wherein the shape memory polymerfoam pivots the first shape memory polymer portion about the secondshape memory polymer portion when the shape memory polymer foam is inits primary shape and also when the shape memory polymer foam is in itssecondary shape; wherein an adhesive couples the shape memory polymerfoam to the carrier element with the adhesive adhering to the carrierelement and the shape memory polymer foam adhering to the adhesive;wherein the adhesive includes an additional polymer.
 2. The system ofclaim 1, wherein the shape memory polymer foam in the secondary shapehas a second modulus and in the primary shape has a first modulus, thesecond modulus being greater than the first modulus.
 3. The system ofclaim 2, wherein the shape memory polymer foam is greater than 5 cm inlength.
 4. The system of claim 2, wherein: the carrier element includesa coil; the first and second shape memory polymer portions are severedfrom one another and no other shape memory polymer portion is betweenthe first and second shape memory polymer portions; the coil includes asection located between the first and second shape memory polymerportions.
 5. The system of claim 2, wherein the additional polymerincludes urethane.
 6. The system of claim 5, wherein the additionalpolymer includes a thermosetting shape memory polymer.
 7. The system ofclaim 5, wherein the shape memory polymer foam is included in a firstlayer and the additional polymer is included in a second layer.
 8. Thesystem of claim 5, wherein the carrier element includes a polymer. 9.The system of claim 8, wherein the carrier element includes a shapememory polymer.
 10. The system of claim 2, wherein the carrier elementincludes a polymer.
 11. The system of claim 10, wherein the shape memorypolymer foam is radiopaque.
 12. The system of claim 10, wherein theshape memory polymer foam has a glass transition temperature less than37.7 degrees Celsius.
 13. The system of claim 10, wherein the first andsecond shape memory polymer portions are monolithic with each other. 14.An implantable system to fill an anatomic void, the system comprising: acarrier element; and a shape memory polymer foam on the carrier element,the shape memory polymer foam having primary and secondary shapes andincluding first and second shape memory polymer portions; wherein theshape memory polymer foam pivots the first shape memory polymer portionabout the second shape memory polymer portion when the shape memorypolymer foam is in its primary shape and also when the shape memorypolymer foam is in its secondary shape; wherein an adhesive couples theshape memory polymer foam to the carrier element with the adhesiveadhering to the carrier element and the shape memory polymer foamadhering to the adhesive, characterized in that the adhesive includes anadditional polymer.
 15. The system of claim 14, the system comprising:an additional shape memory polymer foam on the carrier element, theadditional shape memory polymer foam having primary and secondary shapesand including first and second shape memory polymer portions; whereinthe additional shape memory polymer foam pivots the first shape memorypolymer portion of the additional shape memory polymer foam about thesecond shape memory polymer portion of the additional shape memorypolymer foam when the additional shape memory polymer foam is in itsprimary shape and also when the additional shape memory polymer foam isin its secondary shape; wherein the adhesive couples the additionalshape memory polymer foam to the carrier element; the additional shapememory polymer foam adhering to the adhesive; wherein a space along thecarrier element is present between the shape memory polymer foam and theadditional shape memory polymer foam.
 16. The system of claim 15,wherein the additional polymer includes a thermosetting shape memorypolymer.